1. Field of the Invention
The present invention relates to a setting device for the control surface of a projectile, which includes a drivable spindle or actuated screw which is screwed through the intermediary of a nut which is secured against rotation, and including end stops for limiting the axial extent of displacement of the nut when stop surfaces which rotate in conjunction with the spindle contact in the direction of rotational movement, a stop against a stop surface axially-parallel protruding from a single-threaded helicoid surface on one or the other end face of the nut.
2. Discussion of the Prior Art
A setting device of the foregoing type has become generally known from the disclosure of German Published Patent Appln. 1 065 241 as a so-called screw drive which; for instance, is employed for the actuation of positioning or setting installations. The movement of the nut along the spindle or actuated screw is limited by means of pins which engage radially into the screwthreads of the spindle, against which there presently comes into contact a shoulder on the end surface of the nut along the circumferential direction of the spindle, so as to avoid an axial wedging between contact surfaces. The foregoing also applies to the non-jamming actuated screw and nut combination which is disclosed in U.S. Pat. No. 2,944,436.
In contrast therewith, in a setting device for control surfaces as disclosed in German Laid-Open Patent Appln. 37 02 733, there is encountered the danger that the running nut and, as a consequence, the operational component which is adjusted or controlled thereby (in that instance the control surface of a projectile) will remain caught in the one or the other end position and, as a result, lead to serious adverse influences over the functioning thereof, inasmuch as the screwthreads of nut are too excessively tightened against the screwthreads of the spindle or actuated screw, when the contact surfaces additionally provided at that location and which extend at the end surfaces transversely of the longitudinal axis of the spindle, are brought into contact with each other; for example, at a high rate of speed. Resultingly, the high kinetic energy of the displaced masses are converted into a tightening torque of the nut against the corresponding facing or mating surface, so that quite possibly the torque of the drive motor for effectuating the spindle-driven nut movement will together no longer be adequate to be able to again release this reciprocal tightening.
Such kinetic conditions are not encountered, when there is selected a contacting movement with the least possible axial components, as in the case of a contact movement which is oriented in a circumferential direction so as not to cause any bracing of the paired screwthreads, but at an oppositely directed driving motion, the contact surface can again simply lift away from each other transversely of the longitudinal direction of the spindle. In any event, it is critical that in order to overcome higher forces (especially such as are encountered during the setting of the control surfaces of rapidly-flying projectiles or missiles) so as to avoid the end stopping-jamming effect encountered in the prior art of the type described herein weakening the structure of the setting spindle due to radially inwardly engaging contact pins, and also the dynamic stressability of such pins against contact surfaces oncoming at full setting speed and under a high load is, at the very least, critical. Thus, it is possible to implement braking measures, but this would restrict the usable extent of setting for the running nut, and necessitate the employment of additional, functionally critical, as well as complex assembling measures.